Solar cells are increasingly becoming a more desirable form of energy production. A solar cell operates by converting absorbed photons into electrical current. Therefore, in order to operate at maximum efficiency, a solar cell should absorb as many useful photons as possible. However, for commonly used single-crystalline solar cells, more than 35% of the light incident on the cells is reflected from the surface. In an effort to combat the reflective effects of solar cells, manufacturers have developed various antireflection coatings (ARCs), such as quarter-wavelength silicon nitride (Si3N4) thin films deposited by plasma-enhanced chemical vapor deposition. However, it has been discovered that commercial Si3N4 ARCs are highly wavelength dependent, and when they are designed to exhibit low reflectivity at wavelengths around 600 nm, the reflectivity increases to more than 10% for other relevant wavelengths.
Due to the shortcomings of ARCs, surface texturing of solar cells has been offered as an attractive alternative approach to reduce reflectivity across a broader wavelength range. The effect of such texturing is to control the direction of the light within the solar cell substrate to maximize the propagation distance within the substrate, thereby maximizing the absorption. Efforts to improve light collection capabilities of photovoltaic devices, by adopting the efficient texturing designs have greatly increased. Most surface texturing has thus far been accomplished by photolithographic patterning followed by wet etching. Fabrication of small (sub-wavelength) features requires resist patterned by e-beam lithography or interference lithography, which are expensive processes and not readily scalable to large area for low-cost, high-volume manufacturing.
It would therefore be desirable to have a method of texturing the surface of light-absorptive substrates that was more efficient, lower cost, and easily scalable for high-volume manufacturing.